Manufacturing apparatus for semiconductor device and manufacturing method for semiconductor device

ABSTRACT

A manufacturing apparatus for a semiconductor device, treating a SiN film formed on a wafer with phosphoric acid solution, including a processing bath to store phosphoric acid solution provided for treatment of the wafer, a control unit for calculating integrated SiN etching amount of the phosphoric acid solation, determining necessity of quality adjustment of the phosphoric acid solution, based on correlation between the integrated SiN etching amount calculated and etching selectivity to oxide film, and calculating a quality adjustment amount of the phosphoric acid solution as needed, and also including a mechanism to adjust the quality of the phosphoric acid solution based on the quality adjustment amount calculated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2007-149465 filed on Jun. 5,2007, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing apparatus for asemiconductor device and a manufacturing method for a semiconductordevice, used for etching treatment of a semiconductor substrate, forexample, with phosphoric acid solution.

2. Description of the Related Art

In the manufacturing processes of semiconductor devices, there is aprocess of etching a silicon nitride (SiN) film formed on a wafer withphosphoric acid solution, hereinafter referred to as “H₃PO₄ solution”.This process uses a batch processing bath subjected to etchingtreatment, for example, with a plurality of wafers as one lot. Usually,H₃PO₄ solution is maintained at a temperature of approximately 160° C.next to boiling point in the processing bath, and is used while beingcirculated for treatment of a plurality of lots.

When etching treatment of a SiN film formed on a wafer using H₃PO₄solution is performed in the batch processing bath, etching residueresulting from silica (SiO₂) generated by an etching reaction remains inthe H₃PO₄ solution. By circulating the H₃PO₄ solution and repeatedlyusing the solution for H₃PO₄ treatment, etching residue gathers in theH₃PO₄ solution as the number of lots to be treated increases, and theamount of etching residue increases.

The etching residue causes dust generation and fluctuates SiN etchingrate and etching selectivity to oxide film with the amount of etchingresidue gathered in H₃PO₄ solution. Accordingly, to restrain processfluctuations, there have been studied various methods for controllingthe concentration of etching residue (Si concentration) dissolved inH₃PO₄ solution.

For example, U.S. Pat. No. 6,780,277 has disclosed a method foradditionally supplying H₃PO₄ solution by directly monitoring Siconcentration in H₃PO₄ solution and discarding a required amount ofsolution when the concentration has reached a predeterminedconcentration. For this method, a dedicated Si concentration measurementunit for measuring Si concentration in high-temperature H₃PO₄ solutionwith the in-situ technique is essential. However, such a unit exists inreality, but is very expensive and has questionable reliability.

There has been known a method for controlling Si concentration in H₃PO₄solution to have a desired concentration by adding an appropriate amountof hydrofluoric acid (HF) into H₃PO₄ solution and vaporizing SiO₂byreaction with HF. This method requires measurement of Si concentrationin H₃PO₄ solution. However, it is difficult to control H₃PO₄ solution inreal time, as described above.

US2005/0263488 has disclosed a method for re-precipitating silicate bycooling H₃PO₄ solution and removing the re-precipitated silicate byfiltration. However, the method requires use of a dedicated coolingsystem.

Japanese Patent Application Laid-Open No. 2004-288963 (paragraph numbers[0030] to [0033], FIG. 3 and others) has proposed a method fordetermining a current etching rate of H₃PO₄ solution based on the usehistory of H₃PO₄ solution up to now and data showing a relationshipbetween the use history and etching rate and correcting etching time inaccordance with the etching rate. This method requires no actualmeasurement of Si concentration by the in-situ technique during etchingtreatment.

However, this method allows completion of etching treatment of a desireddepth, but requires long treatment time and therefore a desired apertureshape maybe difficult to obtain due to a relationship with etchingselectivity to oxide film.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, amanufacturing apparatus for a semiconductor device, treating a SiN filmformed on a wafer with phosphoric acid solution, including a processingbath to store phosphoric acid solution provided for treatment of thewafer, a control unit for calculating integrated SiN etching amount ofthe phosphoric acid solution, determining necessity of qualityadjustment of the phosphoric acid solution, based on correlation betweenthe integrated SiN etching amount calculated and etching selectivity tooxide film, and calculating a quality adjustment amount of thephosphoric acid solution as needed, and also including a mechanism toadjust the quality of the phosphoric acid solution based on the qualityadjustment amount calculated.

In accordance with a second aspect of the present invention, Amanufacturing method for a semiconductor device treating a SiN filmformed on a wafer is treated with phosphoric acid solution, includingcalculating integrated SiN etching amount of phosphoric acid solutionprovided for treatment of the wafer, determining necessity of qualityadjustment of the phosphoric acid solution based on correlations betweenthe integrated SiN etching amount calculated and etching selectivity tooxide film, calculating a quality adjustment amount of the phosphoricacid solution determined to be necessary, adjusting quality of thephosphoric acid solution based on the quality adjustment amountcalculated, and treating the wafer using the phosphoric acid solution,the quality of the phosphoric acid solution is adjusted.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which is incorporated in and constitute apart of this specification, illustrates an embodiment of the inventionand together with the description, serve to explain the principles ofthe invention.

FIG. 1 is a schematic view showing configuration of a H₃PO₄ treatmentapparatus according to one embodiment of the present invention;

FIG. 2 is a block diagram illustrating a configuration of a controlunit;

FIG. 3A is a graph illustrating relationship data between integrated SiNetching amount and etching rate stored in a database;

FIG. 3B is a graph illustrating relationship data between integrated SiNetching amount and etching selectivity to oxide film stored in adatabase;

FIG. 4 is a flowchart illustrating an example of treatment with a H₃PO₄treatment apparatus; and

FIG. 5 is a flowchart illustrating another example of treatment with aH₃PO₄ treatment apparatus.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiment of theinvention, an example of which is illustrated in the accompanyingdrawing. Wherever possible, the same reference numbers will be usedthroughout the drawing to refer to the same or like parts.

Referring now to the drawings, embodiments of the present invention willbe described in detail. FIG. 1 is a schematic view showing configurationof a manufacturing apparatus for semiconductor device which allowswafers to be H₃PO₄ treated, hereinafter referred to as a “H₃PO₄treatment apparatus”.

A H₃PO₄ treatment apparatus 100 is so-called a batch treatment apparatusand is installed with a processing bath 10 for H₃PO₄ treatment of waferswith H₃PO₄ solution and a circulation line 11 through which H₃PO₄solution circulates. The circulation line 11 is mounted with acirculation pump 12 for circulating H₃PO₄ solution, a filter 13 forremoving dust in H₃PO₄ solution and a heater 14 for adjustingtemperature of H₃PO₄ solution.

The H₃PO₄ treatment apparatus 100 further has mechanisms for qualityadjustment of H₃PO₄ solution described below. The apparatus includes anew-solution supply mechanism 15 for supplying new H₃PO₄ solution toH₃PO₄ solution to be circulated, solution discharge mechanisms 16, 17for discharging H₃PO₄ solution to be circulated, and a Si componentinput mechanism 18 serving as a mechanism for supplying Si component toH₃PO₄ solution to be circulated.

Further, the H₃PO₄ treatment apparatus 100 includes a wafer carriermechanism 19 for carrying wafers to be subjected to H₃PO₄ treatment ordummy wafers for supplying Si component into/from the processing bathand a control unit 20 for controlling the whole H₃PO₄ treatmentapparatus 100.

The processing bath 10 includes an inner tank 10 a and an outer tank 10b. The inner tank 10 a is installed for storing a sufficient amount ofH₃PO₄ solution to immerse wafers for wafer immersion before H₃PO₄treatment. The outer tank 10 b is installed adjacent to the inner tank10 a and is connected to the circulation line 11. H₃PO₄ solution is madeto overflow, flowed into the outer tank 10 b and introduced into thecirculation line 11.

The circulation line 11 is installed with the circulation pump 12, thefilter 13 and the heater 14 and is connected to the bottom of the innertank 10 a. The H₃PO₄ solution introduced from the outer tank 10 b iscirculated by the circulation pump 12. Dust such as particles in H₃PO₄solution is removed by the filter 13 and H₃PO₄ solution is adjusted to apredetermined temperature by the heater 14. The dust-removed andtemperature-controlled H₃PO₄ solution is introduced into the inner tank10 a again by the circulation line 11.

The new-solution supply mechanism 15 is a mechanism for supplying newH₃PO₄ solution to circulating H₃PO₄ solution in the outer tank 10 b andis controlled by the control unit 20. The new-solution supply mechanism15 may be of such a structure as to supply H₃PO₄ solution to the innertank 10 a.

The solution discharge mechanisms 16, 17 discharges circulating H₃PO₄solution and are controlled by the control unit 20. The solutiondischarge mechanism 16 is branched from the circulation line 11connected to the outer tank 10 b and is used in discharging a relativelysmall amount of H₃PO₄ solution. The solution discharge mechanism 17 isconnected to the bottom of the inner tank 10 a and is used indischarging a large amount of H₃PO₄ solution.

The Si component input mechanism 18 a inputs Si component intocirculating H₃PO₄ solution in the outer tank 10 b and is controlled bythe control unit 20. In the Si component input mechanism 18 a, silicawhich is an etching residue, SiN powder which is a material to be etchedor H₃PO₄ solution having a certain Si concentration is input as aSi-containing material, to adjust Si concentration in H₃PO₄ solution, asneeded.

The wafer carrier mechanism 19 carries wafers w to be subjected to H₃PO₄treatment into/from the processing bath. It may also carry dummy waferson which silicon-containing material or SiN having a known thickness iswholly formed as needed and is controlled by the control unit 20. Thismechanism also has a function for counting with the number of wafers tobe subjected to H₃PO₄ treatment when carrying wafers w into/from theprocessing bath.

When the wafers w are treated in H₃PO₄ solution, the number of productLot of wafers is counted and used for calculating integrated SiN etchingamount as described below. When the dummy wafers are installed intoH₃PO₄ solution, the number of the dummy wafers needed to be installed iscounted.

The control unit 20 is provided to control the whole H₃PO₄ treatmentapparatus 100 including these mechanisms. FIG. 2 is a block diagramillustrating a configuration of the control unit 20.

The control unit 20 is provided with an input/display unit 20 a forinputting operating conditions of the H₃PO₄ treatment apparatus 100,verifying the setting conditions thereof and for displaying operatingstates thereof. The input/display unit 20 a uses, for example, a displayhaving a touch panel function. Through the display, conditions ofetching selectivity to oxide film required for etching treatment areinput. In addition, determined treatment information is displayed.

The control unit 20 has a database 31, a recipe setting unit 32, a countaccumulation unit 33, a treatment determination unit 34, asupply/discharge solution amount calculation unit 35 and a Si componentinput amount calculation unit 36. Each of these components exhibitsfunctions implemented by a computer.

The database 31 stores previously obtained data such as the etchingselectivity to oxide film to integrated SiN etching amount.

The recipe setting unit 32 is input with the etching selectivity tooxide film required for the next wafer to be treated, a wafer treatmentrecipe and the number of wafers to be treated. An icon for input orselection is displayed on the input/display unit 20 a. Based on theinput information, control information of the respective mechanisms isdetermined. The following description uses treatment of substantiallythe same type of wafers (wafers having the same SiN film thickness andaperture ratio) for convenience.

The count accumulation unit 33 counts integrated SiN etching amount inetching treatment performed with current H₃PO₄ solution. The integratedSiN etching amount is obtained by accumulating the product of an etchingamount (depth) in one wafer (e.g. φ300 mm) and the number of treatedwafers for each etching treatment. The number of treated wafers is inputby the recipe setting unit or counted by the wafer carrier mechanism.Counting the integrated SiN etching amount starts when using new H₃PO₄solution.

The treatment determination unit 34 determines whether input the etchingselectivity to oxide film can be implemented by treatment with currentH₃PO₄ solution. In other words, the treatment determination unitdetermines whether solution quality adjustment is required. At thistime, the determination can be implemented by comparing integrated SiNetching amount in the current H₃PO₄ solution with data stored in thedatabase 31.

The supply/discharge solution amount calculation unit 35 and the Sicomponent input amount calculation unit 36 calculate a solution qualityadjustment amount for Si concentration or the like based ondetermination by the treatment determination unit 34.

The supply/discharge solution amount calculation unit 35 calculates adischarge amount of H₃PO₄ solution by the solution discharge mechanisms16, 17 and a supply amount of new H₃PO₄ solution by the new-solutionsupply mechanism 15 when a Si concentration in the current H₃PO₄solution is to be decreased, based on the determination of the treatmentdetermination unit 34.

The Si component input amount calculation unit 36 calculates an amountof Si-containing material to be input into the current H₃PO₄ solution orthe number of dummy wafers to be supplied when Si concentration in thecurrent H₃PO₄ solution is to be increased, based on determination of thetreatment determination unit 34. The Si component input amountcalculation unit 36 may have a selection function for selecting which ofthe Si component input mechanism 18 to use and the dummy wafer tosupply.

As hardware for implementing the functions of the respective units, thecontrol unit 20 has a first storage unit including ROM and hard diskstoring data such as programs and treatment recipes for performingvarious types of control to be performed in the H₃PO₄ treatmentapparatus 100 and database 31 thereof; a central processing unit (CPU)for executing such programs; an input device including input keys forinputting required data and a display; a second storage unit includingsuch as a RAM for temporarily storing treatment data and a hard disk forstoring treatment data. Mutual data exchange is performed between thesecomponents, and the functions of the respective units described aboveare implemented by cooperative operation between hardware and software.

FIGS. 3A and 3B illustrate graphed examples of data stored in thedatabase 31. The data illustrated in FIGS. 3A and 3B are, for example,in combination of [integrated SiN etching amount and etching rate] and[integrated SiN etching amount and etching selectivity to oxide film]and are stored as digital data for each given integrated SiN etchingamount (e.g. 1 nm).

These stored data are previously obtained for use in current H₃PO₄treatment. In obtaining such data, actual results of H₃PO₄ treatmentwhich was actually performed in the past using the H₃PO₄ treatmentapparatus 100.

Counting the integrated SiN etching amount starts when using new H₃PO₄solution. During the counting, H₃PO₄ solution continues to be usedwithout an input of new H₃PO₄ solution into H₃PO₄ solution in use northe discharge of a part thereof on purpose. During this time, theetching rate can be determined, for example, by wafer observation withPhotonic film thickness analyzer or cross-section SEM.

As illustrated in FIG. 3A, as integrated SiN etching amount increases,both SiN etching rate and SiO₂ etching rate decrease. The ratio of adecrease in SiO₂ etching rate to a decrease in SiN etching rate islarge. Accordingly, as illustrated in FIG. 3B, the etching selectivityto oxide film (=SiN etching rate/SiO₂ etching rate) increases asintegrated SiN etching amount increases. In H₃PO₄ treatment, control ofthe selectivity is important in addition to control of the etching rate.

For example, in setting the etching selectivity to oxide film to 50 to60, H₃PO₄ solution having an actual result of 2,000 to 4,200 nm inintegrated SiN etching amount is necessary. When the integrated SiNetching amount of H₃PO₄ solution at present is in excess of 5,000 nm,wafer treatment cannot be performed using this H₃PO₄ solution.Accordingly, there is need of returning the state of current H₃PO₄solution to a state of H₃PO₄ solution having an actual result ofapproximately 2,000 to 4,200 nm in integrated SiN etching amount.

Accordingly, a part of current H₃PO₄ solution is discharged and newH₃PO₄ solution is added. The addition of the new H₃PO₄ solution allowsthe state of H₃PO₄ solution to be returned to a state having smallintegrated SiN etching amount. The integrated SiN etching amount is adissolved Si amount and therefore such an operation itself is the sameas an operation for adjusting Si concentration of H₃PO₄ solution.

Specifically, in adjusting H₃PO₄ solution having integrated SiN etchingamount of 5,000 nm to H₃PO₄ solution having integrated SiN etchingamount of 2,000 nm, it is sufficient to discard 60% of H₃PO₄ solution inuse and then add new H₃PO₄ solution by the same amount as the dischargeamount.

On the other hand, when it is necessary that the etching selectivity tooxide film is, for example, at least 50, solution having an actualresult of 2,000 nm or more in integrated SiN etching amount is required.Accordingly, new H₃PO₄ solution having no actual result cannot performwafer treatment.

To change a state of current H₃PO₄ solution to a state of H₃PO₄ solutionhaving an actual result of approximately 2,000 nm in integrated SiNetching amount, a Si component needs to be supplied. Accordingly,Si-containing material is input or dummy wafer is supplied into currentH₃PO₄ solution.

Supplying a Si component allows new H₃PO₄ solution to have the samesolution quality as the H₃PO₄ solution which has treated a certainnumber of wafers. Addition amount of the Si-containing material or thenumber of dummy wafers to be treated can be obtained, based on theintegrated SiN etching amount.

Accordingly, the discharge amount from current H₃PO₄ solution, theaddition amount of new H₃PO₄ solution, and the addition amount of Sicomponent to be supplied can be determined from the integrated SiNetching amount without need of measurement of actual Si concentration inH₃PO₄ solution.

Referring next to a flowchart illustrated in FIG. 4, description will bemade on a H₃PO₄ treatment flow with the H₃PO₄ treatment apparatus 100.The time point when H₃PO₄ treatment of a predetermined number of wafersis completed with new H₃PO₄ solution is taken as a start point (ST1). Atthis time, counted integrated SiN etching amount is taken as (N). Noadjustment of H₃PO₄ solution is made until ST1 has been reached.

A selectivity to oxide film (S₁) required for the next wafer to betreated are input from the input/display unit 20 a (ST2).

The treatment determination unit 34 determines the selectivity to oxidefilm (S₂) when H₃PO₄ treatment is performed with current H₃PO₄ solution,using the database 31 (ST3).

The treatment determination unit 34 compares the selectivity to oxidefilm (S₁) and (S₂) with each other and determines whether the etchingselectivity to oxide film (S₂) is within the allowable range of theetching selectivity to oxide film (S₁) (ST4).

If the determination is YES in ST4, wafer treatment can be implementedwith current H₃PO₄ solution and therefore H₃PO₄ treatment (ST5) isperformed, without adjustment of H₃PO₄ solution. The integrated SiNetching amount (N) is updated (ST6) and then the process returns to ST1.

If the determination is NO in ST4, the determination unit determineswhether Si concentration in current H₃PO₄ solution is to be lowered(ST7).

The case where the determination is YES in ST7 is a case where SiNetching amount with the current H₃PO₄ solution needs to be small amount.Therefore, the supply/discharge solution amount calculation unit 35determines integrated SiN etching amount (n) of H₃PO₄ solution to beadjusted, from the etching selectivity to oxide film (S₁), using thedatabase 31 (ST8).

The supply/discharge solution amount calculation unit 35 furtherdetermines a discharge amount of current H₃PO₄ solution and an inputamount of new H₃PO₄ solution from the integrated SiN etching amount (N)and the integrated SiN etching amount (n) of H₃PO₄ solution to beadjusted. Based on the determined amounts, H₃PO₄ solution isautomatically adjusted by the new-solution supply mechanism 15 and thedischarge solution mechanisms 16, 17 (ST9). Preferably, circulation ofH₃PO₄ solution through the circulation line 11 is performed for acertain amount of time, so that the composition and temperature of theadjusted H₃PO₄ solution are homogenized.

The H₃PO₄ solution adjusted in this way substantially becomes a H₃PO₄solution having an actual result of the integrated SiN etching amount(n). Accordingly, the previous integrated SiN etching amount (N) isreplaced with integrated SiN etching amount (n) (ST10). That is, “N” issubstituted by “n”. Then H₃PO₄ treatment is performed (ST11). Further,integrated SiN etching amount (N) is updated (ST12) and the processreturns to ST1.

The case where the determination is NO in ST7 is a case where integratedSiN etching amount with current H₃PO₄ solution needs to be largeramount. Therefore, the Si component input amount calculation unit 36determines integrated SiN etching amount (n′) of H₃PO₄ solution to beadjusted, from the etching selectivity to oxide film (S₁) using thedatabase 31 (ST13).

The Si component input amount calculation unit 36 further calculates anSi amount to be input into current H₃PO₄ solution from the integratedSiN etching amount (N), (n′). Next, Si input means (either one or bothof Si component input mechanism 18 and dummy wafer) is determined asneeded, and adjustment of H₃PO₄ solution by the determined means isperformed (ST14).

The H₃PO₄ solution adjusted in this way substantially becomes a H₃PO₄solution having an actual result of the integrated SiN etching amount(n′). Accordingly, the previous integrated SiN etching amount (N) isreplaced with integrated SiN etching amount (n′) (ST15). That is, “N” issubstituted by “n”. Then H₃PO₄ treatment is performed (ST16). Further,integrated SiN etching amount (N) is updated (ST17) and the processreturns to ST1.

In the above description, H₃PO₄-treated wafers having the same SiN filmthickness and aperture ratio are used for convenience, but in practice,various types of wafers, such as a wafer having different SiN filmthickness, a wafer having different aperture ratio, a wafer having SiNon both faces or single face, a wafer formed with SiN film as a maskingmaterial in dry process, a wafer having different SiN volume and a waferhaving different Si amount dissolved from the wafer, are treated asneeded.

In treating such wafers having different modes, current H₃PO₄ solutionis adjusted so that a desired the etching selectivity to oxide film areobtained. Accordingly, exact grasp of integrated SiN etching amount incurrent H₃PO₄ solution is required.

As comparison data stored in the database 31, data describing arelationship between [integrated SiN etching amount per predeterminedarea and the etching selectivity to oxide film] are prepared. Theintegrated SiN etching amount per predetermined area refers to,specifically, the integrated SiN etching amount per predetermined area(nm/cm²) or an integrated SiN etching amount (nm/wafer) per single areaof one wafer (φ200 mm or φ300 mm).

Such a data can be determined, for example, by correcting the integratedSiN etching amount of the data illustrated in FIGS. 3A and 3B inconsideration of an aperture ratio in a wafer. Data obtained in advanceby treating various types of wafers may also be used.

The integrated SiN etching amount in current H₃PO₄ solution is graspedas integrated SiN etching amount per predetermined area. As one of themethods, there is proposed a method of providing a function forincluding the SiN film amount practically etched in a treatment recipeas information. Specifically, parameters for automatically calculatingSiN etching amount per predetermined area, such as film thickness,aperture ratio (mask area in the case of etching mask) and presence ofback film are provided. Hence, SiN etching amount per predetermined areain one wafer is exactly grasped, depending upon a selected recipe.

Further, as parameters, information of the number of wafers to betreated is used. This information can be obtained by inputting thenumber of wafers to be treated or counted result by a wafer carriermechanism 19. By using the parameters, integrated SiN etching amount perpredetermined area can be obtained. Such a function may be provided inthe recipe setting unit 32 and the count accumulation unit 33.

There may occur a case where a part of parameters for automaticallycalculating SiN etching amount per predetermined area included in aselected treatment recipe are different from actual parameters of wafersto be treated. Such treatment recipe parameters can be corrected throughthe input/display unit 20 a.

Referring to a flowchart in FIG. 5, brief description will be made onactual wafer treatment when such integrated SiN etching amount perpredetermined area is used.

To sequentially perform a plurality of H₃PO₄ treatments a recipe ispreselected according to the sequence made and the content thereof isstored. Each recipe includes a required etching selectivity to oxidefilm.

In FIG. 5, a state in which predetermined H₃PO₄ treatments have beenperformed and adjustment of H₃PO₄ solution has been completed as neededis taken as a start point. It is verified through a display of theinput/display unit 20 a that the number of wafers to be actually treatedmeets the previously input number of wafers (ST101). When any changesneed to be made, the number of wafers to be actually treated is input,and a treatment recipe is verified (ST102). Hence, the integrated SiNetching amount per predetermined area is updated (ST103) and H₃PO₄treatment is started (ST104).

In the treatment according to the flowchart in FIG. 4, integrated SiNetching amount with H₃PO₄ solution at that point in time is updatedafter completion of predetermined batch treatment. The integrated SiNetching amount per predetermined area may be updated before actual batchtreatment in the sane way as the treatment according to the flowchart inFIG. 5.

After completion of the batch treatment in ST104, it is determinedwhether or not the etching selectivity to oxide film included in arecipe for the next batch treatment can be obtained with H₃PO₄ solutionafter completion of the batch treatment in ST104. Specifically, it isdetermined whether or not the quality adjustment of H₃PO₄ solution(H₃PO₄ solution discharge/additional supply of new H₃PO₄ solution or Sicomponent addition) is necessary (ST105).

When the quality adjustment of H₃PO₄ solution is necessary, theadjustment (ST106) is automatically performed, thus leading to a nextbatch treatment standby state (ST107). On the other hand, when H₃PO₄solution adjustment is not necessary, the process goes into a next batchtreatment standby state without adjustment. Then, the process returns toST101.

The embodiment of the present invention has been described above, butthe present invention is not limited thereto. For example, H₃PO₄solution adjustment to a substantially same state before startingrespective H₃PO₄ treatments allows continuous H₃PO₄ treatment under thesame conditions.

For quality adjustment of H₃PO₄ solution, Si component has been added,but adjustment by HF addition is also applicable.

As described above in detail, the present embodiment enables easyadjustment, by in-situ technique, of H₃PO₄ solution capable of obtaininga required etching selectivity to oxide film for H₃PO₄ treatment withoutneed of an expensive system. Accordingly, stable and etching selectivityto oxide film can be obtained in H₃PO₄ treatment. Variations incharacteristics of wafers subjected to H₃PO₄ treatment and semiconductordevices formed therewith can be suppressed, so that the yield thereofcan be boosted.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A manufacturing apparatus for a semiconductor device, treating a SiNfilm formed on a wafer with phosphoric acid solution, comprising: aprocessing bath to store phosphoric acid solution provided for treatmentof the wafer; a control unit for calculating integrated SiN etchingamount of the phosphoric acid solution, determining necessity of qualityadjustment of the phosphoric acid solution, based on correlation betweenthe integrated SiN etching amount calculated and etching selectivity tooxide film, and calculating a quality adjustment amount of thephosphoric acid solution as needed; and a mechanism to adjust thequality of the phosphoric acid solution based on the quality adjustmentamount calculated.
 2. The manufacturing apparatus for a semiconductordevice according to claim 1, wherein the control unit includes a storageunit to store correlation between a previously obtained integrated SiNetching amount and etching selectivity to oxide film.
 3. Themanufacturing apparatus for a semiconductor device according to claim 1,wherein the mechanism to adjust the quality of phosphoric acid solutionincludes a mechanism for supplying new phosphoric acid solution and amechanism for discharging the phosphoric acid solution.
 4. Themanufacturing apparatus for a semiconductor device according to claim 1,wherein the mechanism to adjust the quality of phosphoric acid solutionincludes a mechanism for supplying silicon component.
 5. Themanufacturing apparatus for a semiconductor device according to claim 4,wherein the mechanism for supplying silicon component is a mechanism forsupplying a dummy wafer formed with a predetermined silicon-containingmaterial or a predetermined SiN film.
 6. The manufacturing apparatus fora semiconductor device according to claim 1, further comprising acirculation line for circulating the phosphoric acid solution.
 7. Themanufacturing apparatus for a semiconductor device according to claim 6,wherein a filter is provided on the circulation line.
 8. Themanufacturing apparatus for a semiconductor device according to claim 6,wherein a heater is provided on the circulation line.
 9. A manufacturingmethod for a semiconductor device treating a SiN film formed on a waferis treated with phosphoric acid solution, comprising: calculatingintegrated SiN etching amount of phosphoric acid solution provided fortreatment of the wafer; determining necessity of quality adjustment ofthe phosphoric acid solution based on correlations between theintegrated SiN etching amount calculated and etching selectivity tooxide film; calculating a quality adjustment amount of the phosphoricacid solution determined to be necessary; adjusting quality of thephosphoric acid solution based on the quality adjustment amountcalculated; and treating the wafer using the phosphoric acid solution,the quality of the phosphoric acid solution is adjusted.
 10. Themanufacturing method for a semiconductor device according to claim 9,wherein the integrated SiN etching amount is calculated based on arecipe of wafers treated with the phosphoric acid solution and thenumber of the wafers.
 11. The manufacturing method for a semiconductordevice according to claim 10, wherein the recipe is prepared inplurality and the integrated SiN etching amount is calculated accordingto the respective recipes.
 12. The manufacturing method for asemiconductor device according to claim 10, wherein the recipe hasparameters of thickness of SiN films formed on the wafers, an apertureratio of the SiN films, presence of a back SiN film and number of thewafers to be treated.
 13. The manufacturing method for a semiconductordevice according to claim 9, wherein the integrated SiN etching amountis determined as a SiN film thickness per unit area of a wafer.
 14. Themanufacturing method for a semiconductor device according to claim 9,wherein the necessity of the quality adjustment of the phosphoric acidsolution is determined, by comparing correlation between integrated SiNetching amount and etching selectivity to oxide film stored in advancein a database with the integrated SiN etching amount calculated.
 15. Themanufacturing method for a semiconductor device according to claim 14,the necessity of the quality adjustment of the phosphoric acid solutionis determined, by obtaining etching selectivity to oxide film estimatedfrom the integrated SiN etching amount calculated based on the databaseand determining if the etching selectivity to oxide film is within apredetermined range.
 16. The manufacturing method for a semiconductordevice according to claim 14, the necessity of the quality adjustment ofthe phosphoric acid solution is determined, by calculating integratedSiN etching amount required for treatment from a required range of theetching selectivity to oxide film based on the database and comparingthe integrated SiN etching amount with the integrated SiN etching amountcalculated required for the treatment.
 17. The manufacturing method fora semiconductor device according to claim 9, wherein the quality of thephosphoric acid solution is adjusted by discharging the phosphoric acidsolution and supplying new phosphoric acid solution.
 18. Themanufacturing method for a semiconductor device according to claim 17,wherein the quality of the phosphoric acid solution is adjusted bysupplying a silicon component into the phosphoric acid solution.
 19. Themanufacturing method for a semiconductor device according to claim 17,wherein the quality of the phosphoric acid solution is adjusted bysupplying a dummy wafer formed with a predetermined silicon-containingmaterial or a predetermined SiN film into the phosphoric acid solution.20. The manufacturing method for a semiconductor device according toclaim 17, wherein the phosphoric acid solution is circulated.